The present invention relates to a new and improved construction of an apparatus for generating hoistway data in an elevator.
In its more particular aspects the present invention specifically relates to a new and improved construction of an apparatus for generating hoistway data in an elevator. In such apparatus, an elevator car is connected with a position transmitter by means of which there can be determined elevator car positions which are coincident at least with predetermined hoistway locations.
Predetemined hoistway locations are represented by binary numbers in an elevator control system as known, for example, from Swiss Patent No. 357,173. For the purpose of generating signals corresponding to the binary numbers, a coding apparatus is proposed in which four transmitted elements in the form of snap action switches fastened to the elevator car and by means of which two different stationary switching conditions can be produced. These snap action switches are actuated when the elevator car passes-by actuating members in the form of slideways positioned in the elevator hoistway. In order to keep the number of actuating members as small as possible, the coding is based on the Gray code and in this manner only one actuating member is required per hoistway location. The coding apparatus, which operates on a mechanical principle, is prone to malfunction so that faulty switching operations can occur.
In an apparatus as known, for example, from Swiss Patent No. 622,226, the aforementioned disadvantage is avoided. In this apparatus the transmitters fastened to the elevator car, comprise bi-stable magnetic switches and the actuating members which are arranged in the elevator hoistway, comprising switching magnets.
One disadvantage of the above described apparatuses lies in the fact that the expenditure required for support means for the installation of the actuating members in the elevator hoistway as well as for the installation and setting-up operations is substantial and even increases with the number of floors and the hoistway data necessary for the control system. Moreover, four-digit transmitters are not sufficient in many elevator installations for collecting all hoistway data so that more than four conductors must be provided in the travelling cable for the signal transmission.
An actual value transmitter associated with a position control circuit and as known for example from European Patent No. 0,026,406, comprises a pulse transmitter in the form of a digital tachometer. The digital tachometer is driven by the elevator car by means of a cable of an overspeed governor and generates one pulse for every 0.5 mm of travel distance. The pulses are summed up in a car travel distance counter to positional numbers which are utilized as actual values for the regulation of travel.